1. Field of the Invention
The present invention is directed to a method for determining a requirement to replace a component of an apparatus and to an apparatus for the implementation of the method. The apparatus can be a postal security module that, in particular, is suited for use in a postage meter machine or mail processing machine or a computer with a mail-processing function and that allows a battery replacement.
2. Description of the Prior Art
Various security measures are known for protection against outages or malfunctions of intelligent electronic systems. European Application 417 447 already discloses the use of special modules in data processing systems, equipped with means to protect against forced entry into their electronics. Such modules are called security modules below.
Mail processing systems are now modularly constructed in order to be able to make use of a large number of existing modules in different product versions. This procedure eliminates the constant redevelopment of functions for utilization in new versions of systems. Modules are designed such that they can execute at least one function that is to be utilized in different versions. A further advantage of modularly constructed systems is the economic and simple replacement of a module when the module is used up or fails. Display of the consumption of a module and providing a warning about the future outage of a module are means that enable such modules to be replaced in time and are currently included in the service design of modern mail processing systems. Various techniques are in use for this service feature. German OS 195 49 376 discloses an arrangement for determining a remaining amount of an inking ribbon for thermal transfer printing processes wherein the approach of the end of the inking ribbon is determined by an optical recognition unit that detects a mark on the inking ribbon, or by a control means that counts the number of fixed-size imprints. The latter solution assumes a linear relationship between the number of imprints and the length of the inking ribbon.
In the case of consumables such as ink from print heads, direct measurements or statistical counting techniques can be utilized in order to undertake a determination of the material that has been consumed. Despite the non-linear relationship between remaining ink quantity and the number of imprints, German OS 199 58 948 discloses a method for determining the number of imprints that can be executed with a remaining ink quantity and discloses an arrangement for the implementation of this method. A pre-condition, however, is that the ink tank cassette is not a pirated product but an original product that is supplied filled with a defined quantity of ink.
An early recognition of an outage is desirable for all components, assemblies or modules that, for example due to their physical structure, have a shorter service life than that of the overall mail processing system. German OS 199 12 780 discloses that the security module be equipped with a replaceable battery. Based on empirical values about the power consumption of the security module and knowledge of the nominal capacity of the battery, the manufacturer of the security module estimates the likely battery service life and the battery thus is changed in time with a safety margin. A premature change, however, adds cost, particularly since the battery is a an expensive long-life lithium battery.
Here, as well, known techniques can be utilized in order to provide warnings in time, for example to report the necessity to change a battery. Usually, a date threshold is defined and the transgression thereof triggers the alarm based on a date counting procedure. It is possible, however, that the corresponding component or module is not yet completely used up or will not soon fail. Often, the defined threshold is dependent on various parameters during operation (for example, temperature, humidity). These parameters can shift the actual threshold substantially. The result can be that the consumption is higher or lower than the specified threshold or that the outage can ensue earlier or later under certain operating conditions. In all of these cases the user or the owner of the system can incur a variety of financial losses that must be prevented. Direct measurements must be individually configured dependent on the component or module and can quickly increase the unit costs if a number of components or modules are to be monitored. Further, the functioning of some components or modules is impaired due to direct measurement techniques. Thus, for example, the act of making a capacity measurement of a battery can considerably shorten the service life if the normal power consumption is lower than that needed for the measurement.
A security module can assume various statuses in its life cycle that can only be displayed when system voltage is present. Otherwise, the battery of the security module would be quickly depleted. The service life of the battery should be appropriate for the life cycle and should be optimally long. When the postage meter machine is turned off, given power interruptions or a system voltage outage, the postal register data, cryptographic keys and other sensitive data must be preserved and the real-time clock must also continue to run. Permanent monitoring functions that must continue to run interruption-free also must not be compromised. As a result, the need for available battery power increases, with the result that the service life of the battery is shortened.
An object of the invention is to provide an apparatus and a method for determining a requirement to replace a component, wherein the measurement of a parameter is avoided for which measurement thereof would have an unbeneficial influence on the consumption or on the service life of the component. The dependability of preventing an outage, particularly of components with battery-supported data stores, must be enhanced and the service life of the battery must be optimally exploited at the same time. The apparatus and method can be employed, for example, in postage meter machines for which there are special security demands with respect to the postal register data with the monetary accounting data.
The object is achieved in a method and an apparatus in accordance with the invention wherein indirect measurement techniques are used that deliver a warning indication in time before the outage of a module after the implementation of at least two time-offset parameter measurements. Arbitrarily scalable measurements of the most important parameters that influence the consumption or outage of a component or module are undertaken. When not yet determined by the manufacturer, these parameters are empirically determined with test sequences and, for example, are deposited in table form. Dependent on a measured quantity, a predetermined change of the consumption or of the outage of a component or module is then found for each parameter. In addition to the normal statistical acquisition by counting techniques that was is undertaken in known systems, the measured parameter quantityxe2x80x94by its absolute or percentage changexe2x80x94can now have a suitable (positive or negative), additional influence, namely on the counting technique. Given a number of parameters, correspondingly more influences exist. An indirect measurement arises in this way that can be utilized so that a significantly more precise indication of the new warning threshold for the consumption or outage of a component or module is obtained. For example, a count reading can be modified such that it approaches a failure threshold specified for the component and such that the device emits a warning before the end of consumption or end of the service life of the component is reached. An arrangement for the implementation of the method has a timer for outputting a time parameter, at least one sensor for the measured value registration of a parameter, at least one component whose outage is influenced by this parameter, a microprocessor that is connected to the sensor and to the timer, a memory that contains specific values for this parameter, a memory that stores a count reading that determines the outage of the component part and a program memory that is connected to the microprocessor. The microprocessor executes a function stored in the program memory that, dependent on the measured value of the parameter, the time parameter and the count reading, modifies the count reading such that it approaches an outage threshold specific for the component and generates a warning when it reaches the threshold. This indirect measurement outlay and setup can be performed once and simultaneously utilized for a number of different components or modules when the characteristics of the influencing parameters are known and are likewise evaluated. The processor of a security module monitors the battery with respect to service life, monitors the hardware-implemented accounting unit and memory with respect to the accounting function or data, as well as monitoring other assemblies with respect to further functions. The continued availability of the system is the primary factor, as is a suitable reaction when needed.
The invention is explained below with reference to the example of battery monitoring. The requirement to replace the battery is identified by an evaluation of a measurement of the ambient temperature of the battery and a time measurement. A direct current/voltage measurement that burdens the capacity of the battery is thus eliminated. The evaluation of a measurement of the ambient temperature ensues with reference to the self-discharge current of the battery. Due to an uninterrupted real-time measurement, a microprocessor can determine time intervals, whereby a distinction is made between a transport time interval as well as operating and quiescent time intervals of the device. The measurement and the evaluation of the ambient temperature with reference to the self-discharge current of the battery ensues in the operating time interval, i.e. after the transport time interval or after a quiescent time interval of the device. In the evaluation, current/time products are formed for the aforementioned intervals in the operating time interval, whereby empirically determined currents enter into the calculation, which flow in the transport time interval or in the quiescent time interval of the device and diminish the battery capacity.